Diazene

Diazene, also known as diimide, is the simplest diazene with formula N2H2. In the canonical structure it consists of an N=N double bond with one hydrogen on each nitrogen, giving HN=NH. Two geometric isomers are possible: cis-diazene and trans-diazene; the trans form is usually more stable.

Diazene is highly reactive and difficult to isolate at room temperature. It is typically generated in situ or studied as a transient intermediate by controlled oxidation or dehydrogenation of related hydrazine derivatives.

As a reagent, diimide is used as a mild hydrogen donor for the selective hydrogenation of alkenes. It adds two hydrogen atoms syn to the double bond, converting alkenes to alkanes with nitrogen gas as a benign byproduct.

Because of its instability, diazene requires low-temperature handling and careful safety precautions. It can decompose or rearrange under improper conditions.

See also: Hydrazine, Diimide hydrogenation, Nitrogen gas.